The present invention relates to a rotary pelletizing machine.
More particularly, it relates to a rotary pelletizing machine with rotatably supported matrix disc, a plurality of upper and lower plungers provided in the matrix disc so that their position during rotation of the matrix disc is controlled by rails or pressing rollers, and holders for holding the lower plungers from falling out of the matrix disc during dismounting.
When pelletizing machines are used it is necessary to convert a machine for subsequent manufacture of other pellet types or for cleaning of individual machine parts. For an efficient utilization of a pelletizing machine it is advantageous when the time for such a conversion of the machine or for cleaning its machine parts is as short as possible in comparison with the operation time or the production time. For maintaining as short as possible the time required for a conversion of the machine for example for a different plunger pitch or another plunger pressure or for cleaning it is advantageous when the matrix disc with the upper and lower plungers can be exchanged as simple as possible. At the same time it is necessary to hold the lower plungers so that they are securely maintained in the matrix disc and do not fall out of the latter during the dismounting. Known arrangements for such a securing possess certain disadvantages with respect to the above mentioned short time requirement.
The lower plungers must not fall out of the matrix disc when the lower control cams are dismounted or when during an exchange of the matrix disc the lower pressing rollers and guiding rails release individual lower plungers. For this purpose the lower plungers which are used in great numbers in the machine are provided with individual holders. These known holders for the individual lower plungers include a pressure member which is clamped radially against a plunger shaft of the lower plunger. For securing each individual lower plunger in the machine in which a matrix disc for example has 80 pieces, a corresponding number of the pressing pieces must be used with an exactly predetermined torque. This is naturally associated with significant mounting expenses. The individual pressing pieces must be secured so that they are not loosened. When during the operation individual synthetic plastic heads of the pressure pieces are worn, they must be individually exchanged.